(CNN) -- Anti-China protesters gathered Saturday in Tokyo and six other major cities in Japan to rally against what it calls an invasion of disputed islands that both claim are part of their territories.

Protesters held up Japanese flags and chanted, "We will not allow Communist China to invade our territory."

Beijing says the Diaoyu Islands and most of the South China Sea belong to China, disputing neighboring countries' claims. In Japan, the islands are known as the Senkaku.

The rally was organized by Toshio Tamogami, a former Japanese chief of staff for the Self Defense Force.